Hakim Dhibi

Task 1 (B)

Gas laws

05/02/2013

Often deals with liquids and gases that exert forces on their containers, for example the fluids exert pressure over an area. If the container changes volume, then this force acts through a distance and hence does work.

For a steam engine, the example pictured here, the "container" is a cylinder whose volume changes as the piston slides in or out. Suppose a gas is confined within the cylinder. The pressure of the gas is P, and the area of the cylinder is A. Consider the work done as the gas expands, pushing the piston to the right. Call the infinitesimal distance the piston moves

For example the force does the gas exert on the piston, which the positive x axis is to the right in the figure. The force in terms of A and P and any constants, will be the same F= A X B

Modern refrigerators use a type of gas called HFC-134a, also called tetrafluoroethane. HFC turns into a liquid when it is cooled to -15.9 degrees Fahrenheit (-26.6 degrees Celsius). A motor and compressor squeezes the HFC. When it is compressed, the gas heats up as it is pressurized. When you pass the compressed gas through the coils on the back or bottom of a modern refrigerator, the warmer gas can lose its heat to the air in the room. As it cools, the HFC can change into a liquid because it is under a high pressure.